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Calculating the cut outs

This page provides extra information from the page on composition using framing

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Calculating cut-outs to fit proportions

Proportionate to your camera sensor

You can get the proportions of your camera sensor from your instruction manual or by looking at the size of an image in an editing program before you edit it at all. You can then determine the proportion of width to height.

An example

If I take an unedited Nikon D200 RAW photograph and look at it in an editing program, it tells me that at 300 DPI the image size is 32.78cm wide by 21.95cm high.

If we divide 32.78 by 21.95 we get 1.5, therefore the proportions are 1 to 1.5 often written 1:1.5

Most of the cameras that are in the same manufacturers format will have the same cut-out size, so with the example I am using it would also work for very many of the Nikon DSLR's, such as the D70, D80, D90, D300 etc.

Full frame 35mm film is 24mm by 36mm so this is also 1:1.5

Calculating the cut-out

Now we know the proportions we can just multiply the size we want to use for the shorter length, by the proportion above. So for example, we might decide that a cut-out had a shortest side of 4 inches, then the longest side using the D200 above would be 4x1.5 = 6 inches. So our cut-out would be 4x6 inches.

In the piece of card I was using, allowing for reasonable sized edges so the elastic bands did not break it, I decided to use a cut out of 12cm on the shorter side, so 12x1.5 = 18, so my cut out would be 12x18 inches.

You can use any unit, cm, inches, ... as long as you use the same unit throughout.

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